I had an email and text on 31 Dec from Amex with a numeric safety code which I hadn't requested. I immediately checked my Amex app and saw a transaction for nearly £300 for John Lewis. I immediately called them (was away on holiday at the time) and the operator told me that Amex was being inundated with calls from people reporting JL fraud. Card cancelled and told I had to call the fraud line - LONG wait times. Called them two days later when back off holiday. Still waiting for replacement card.
I too was subject to the BA data breach hack. I was told by Amex they would be looking out for suspicious transactions - this didn't happen. I had to alert them. Maybe I should have done what my friend did: cancel my card a few months ago.